This way up: Source of brain dizziness identified

Feeling dizzy? A part of the brain that tells "up" from "down" may be the cause, new research finds.

Researchers zapped people's brains with magnetic pulses, identifying a brain region that triggered spatial disorientation. The area could be a target for treating people with disorienting dizziness, the researchers say.

Damage to the inner ear or vision can cause dizziness. Vertigo, the feeling that one's surroundings are spinning, can stem from crystals in the inner ear that become dislodged, creating the sensation of movement.But sometimes the problem arises from brain processes that convert sensory input into the perception of up and down. [5 Most Controversial Mental Health Treatments]

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"Our brain has this amazing way of knowing where we are in space, whether we are upright or tilted at an angle, even if it is completely dark and we can't see anything around us," study researcher Dr. Amir Kheradmand, a neurologist at Johns Hopkins University School of Medicine in Baltimore said in a statement.

Experiments in zero gravity indicate the human brain uses gravity to tell which way is up. And studies of stroke victims suggest damage to a brain area called the right parietal cortex causes problems with upright perception.

Kheradmand and his colleagues took a closer look. They put people in a dark room with a computer screen showing a series of tilted lines, and told them to report the orientation of the lines by moving a dial to the left or right.

Next, participants underwent transcranial magnetic stimulation, or TMS, a noninvasive method of zapping the brain with electromagnetic currents that can temporarily block brain activity in a particular area. The scientists zapped part of the participants' right parietal cortex called the supramarginal gyrus, an area previous studies have shown to be key for processing input from the inner ear and other senses.

Participants received 600 TMS pulses in 40 seconds while they observed the tilted lines. During TMS, people reported their sense of being upright was skewed, and each person's sense was skewed in the same way, the team reported online Oct. 8 in the journal Cerebral Cortex.

The effects of TMS wore off quickly, and people's upright sense returned to normal.

The results of the study suggest TMS could potentially be used to treat chronic dizziness, Kheradmand said in the statement, adding, "We're excited that this could someday be a key to helping people who have dizziness and spatial disorientation to feel better."

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